Accelerated method and instrumentation for whitening teeth

ABSTRACT

The invention provides a composition whitening teeth, using a bleaching compound and a catalytic activator, where the catalytic activator catalyzes the reaction of a significant portion of the bleaching compound within in a short period of time. A method for whitening teeth by providing a bleaching compound, providing a catalytic agent, and combining the bleaching agent with the catalytic agent so that a reaction of a significant portion of the bleaching agent occurs in a short period of time is also disclosed. A device for whitening teeth, consisting of a toothbrush where at least one of the bristles contains a catalytic activator is also provided. The handle of this device has a reservoir for a bleaching compound and a means for dispensing the bleaching compound. Another device for whitening teeth, consisting of a toothbrush with a catalytic activator capable of catalyzing the reaction of a bleaching compound applied to the head of the device, is further provided.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional ApplicationSerial No. 60/048,423, filed Jun. 3, 1997.

FIELD OF THE INVENTION

The present invention relates to the field of dentistry, andspecifically to the whitening of the teeth.

BACKGROUND OF THE INVENTION

Teeth generally become more darkly pigmented with age and exposure tosuch materials as tea and coffee, and it has long been a goal ofdentistry to provide a means to safely and effectively reverse thisdarkening process. Historically there are two approaches to the problem.The first involves removing pigmentation that has adhered onto thesurface of the teeth. This is commonly achieved through the use ofabrasives, sometimes augmented with solvents. While rapidly effective,these techniques have the disadvantage of only being able to removeextrinsic stains, leaving all internal pigmentation unchanged. Thus thewhitening effect is extremely limited.

A more recent innovation involves a method of using oxidizing agents topenetrate into the tooth structure and bleach out the undesiredpigmentation. The active agents are usually either weak solutions ofhydrogen peroxide or carbamide peroxide, which is more stable thanhydrogen peroxide.

While effective on both extrinsic and intrinsic discolorations, onemajor problem encountered with this second approach is the enormousamount of treatment time needed to gain adequate penetration of thetooth structure by the whitening agent. At present, the method ofapplication of the whitening agent utilizes either custom or stock traysthat are shaped to hold the bleaching agent against the teeth to bewhitened. These trays are then filled with the peroxide, and worn forlong periods of time, sometimes even overnight. After a series oflengthy treatments, the teeth will usually begin to show the desiredwhitening effect. The length of these treatments can be discouraging andincreases the cost. It is therefore desirable to find a method to morerapidly whiten the teeth.

SUMMARY OF THE INVENTION

In one embodiment, the invention provides a composition whitening teeth,using an effective amount of a bleaching compound and a catalyticactivator, where the catalytic activator catalyzes the reaction of asignificant portion of the bleaching compound within ten minutes.

In a second embodiment, the invention provides a method for whiteningteeth consisting of providing a bleaching compound, providing acatalytic agent, and combining the bleaching agent with the catalyticagent so that a reaction of a significant portion of the bleaching agentoccurs within ten minutes.

In another embodiment, the invention provides a device for whiteningteeth, consisting of a toothbrush with a head and a handle, where thehead has a plurality of bristles, and at least one of the bristlescontains a catalytic activator. The handle of this device has areservoir for a bleaching compound and a means for dispensing thebleaching compound.

In a further embodiment, the invention provides a device for whiteningteeth, consisting of a toothbrush with a head and a handle, where thehead has an applicator and a catalytic activator capable of catalyzingthe reaction of a bleaching compound applied to the head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a toothbrush made in accordance with thepresent invention that has a compartment for a catalytic activator onthe head.

FIG. 2 is a front elevational view thereof.

FIG. 3 shows a cross section of a toothbrush with bristles containing acatalytic activator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

All publications mentioned herein are incorporated herein by referencefor the purpose of describing and disclosing the equipment,compositions, and methodologies which are described in the publicationswhich might be used in connection with the presently describedinvention.

The invention provides a composition for whitening teeth, consisting ofa therapeutically effective amount of a bleaching compound and acatalytic agent, where the catalytic agent is capable of catalyzing thereaction of a significant portion of the bleaching compound within ashort period of time. A "bleaching compound" is any compound which hasthe ability, when activated by a catalyst, of whitening the teeth.Examples of suitable bleaching compounds include an oxygen radicalgenerating agent such as metal ion free peroxides, organic peroxides,and metal ion containing peroxides. Specific, non-limiting examples ofbleaching agents suitable for use with the subject invention arecarbamide peroxide, carbamyl peroxide, sodium percarbonate, perhydrolurea, and hydrogen peroxide. By "therapeutically effective amount" ismeant the quantity of a the bleaching agent, when placed in contact witha catalyst according to the invention, necessary to whiten the teeth ofa subject. A subject is any mammal, preferably a human.

Typically the bleaching agent employed in the composition in amounts sothat about 3% to 40% by weight comprises the bleaching agent.Preferably, if the bleaching compound is hydrogen peroxide, theconcentration of the bleaching compound is from about 3 to 12% byweight. Most preferably, if the bleaching agent is hydrogen peroxide,the concentration of the bleaching compound is from about 6% to about10% by weight. Preferably, if the bleaching agent is carbamide peroxide,carbamyl peroxide, sodium percarbonate, and perhydrol urea, theconcentration of the bleaching compound is from about 10% to about 40%by weight. More preferably, if the bleaching agent is carbamideperoxide, carbamyl peroxide, sodium percarbonate or perhydrol urea, theconcentration of the bleaching compound is from about 20% to about 30%by weight.

Assays to determine a therapeutically effective amount of a bleachingcompound are known in the art. For example, stained extracted teeth canbe used to measure a whitening effect (see Example 1). Other assays,such as an analysis of the effect of a bleaching compound on the softtissues, may also be used in the determination of a therapeuticallyeffective range of concentrations of a bleaching compound.

The bleaching agent is contained in a vehicle; formulations of vehiclesfor bleaching agents are well known in the art. The formulation can beaqueous or non-aqueous. As an example, glycerin, and polyethylene glycolin combination with water are useful in formulating the vehicle.Thickening or gelling agents may also be used in the formulation of thebleaching agent. In one example poloxyethylene/polyoxypropylene blockcopolymers can be utilized. As another example, carbopol polymers can beused. These polymers are well known in the art, and are availablecommercially.

The composition of the subject invention furtherer consists of acatalytic agent. A "catalytic agent" is a compound or molecule whichaccelerates the whitening action of the bleaching compound without beingconsumed in the reaction. In a preferred embodiment, the catalytic agentaccelerates the release of oxygen radicals from an oxygen radicalgenerating agent. Examples of such agents include, but are not limitedto activated charcoal, platinum, platinum salts, copper, copper salts,palladium, palladium salts, silver, and silver salts. In a preferredembodiment, activated charcoal is used as the catalytic activator. Ofparticular use with the subject invention is the commercially activatedcharcoal Centaur, produced by Calgon, Inc. Catalytic agents useful withthe subject invention catalyze the reaction of a significant portion ofthe bleaching compound within a short period of time of coming intocontact with the bleaching compound. By "short period of time" is meantin minutes, preferably about ten minutes or less. The catalytic agentmay catalyze the reaction of substantially all of the bleaching compoundin about ten minutes of coming into contact with the bleaching agent. Inone embodiment the catalytic activator catalyzes the reaction of 50% ofthe bleaching agent, preferably 70% of the bleaching agent, and morepreferably 90% of the bleaching agent. Contact of the bleaching compoundwith the catalytic agent causes the visable evolution of gas within twominutes of contact. "Visable evolution" of a gas, such as oxygen, formedby the contact of the bleaching compound with the catalytic agent can benoted in many ways, such as the formation of bubbles or any sign ofgaseous release.

In one embodiment, an abrasive material can be used with the compositionof the invention. For example a dicalcium phosphate abrasive may beincorporated into the composition (e.g., see U.S. Pat. No. 5,171,564).Example of dicalcium phosphate abrasives include, but are not limited todicalcium phosphate dihydrate, anhydrous dicalcium, or calciumpyrophosphate. Other abrasives of use with the subject invention includesiliceous materials. Examples of such materials include, but are notlimited to, silica abrasives, such as precipitated amorphous hydratedsilica, and alumina abrasives, such as alumina trihydrate, aluminumsilicate, calcined alumina, and bentonite.

When an abrasive material is included the vehicle may contain water,humectant, surfactant, and a thickener. Examples of humectants areglycerin, sorbitol, and polyethylene glycol (molecular weight 200-1000).Both mixtures of humectants and single humectants can be employed in thecomposition of the invention. Thickeners may be incorporated in theabrasive component such as natural and synthetic gums such ascarrageenan, xantham gum, sodium carboxymethyl cellulose, starch,polyvinylpyrrolidone, hydroxyethylpropylcellulose, hydroxybutyl methylcellulose, hydroxypropyl methyl cellulose, and hydroxyethyl cellulose.

In another embodiment, an agent for administering fluoride, such as afluorine providing salt, which has activity against cavities, may beincorporated into the composition of the subject invention. Suchmaterials are characterized by their ability to release fluoride ions inwater. Agents for administering fluoride include, but are not limitedto, inorganic metal salts such as sodium fluoride, potassium fluoride,and tin fluoride such as stannous fluoride or stannous chlorofluoride,sodium fluorosilicate, ammonium fluorosilicate, and sodiummonofluorophosphate.

The composition may also include palliative ingredients for periodontaltissues. Examples of such ingredients include, but are not limited toaloe, eugenol, and vitamin E. Pigments, sweeteners, colors, and flavorsmay also be incorporated into the composition. The composition mayfurther include an ingredient to decrease tooth sensitivity, such aspotassium nitrate. The addition of these components to dental creams,such as toothpaste, are well known in the art.

The invention further provides a method for whitening teeth, byproviding a bleaching agent, providing a catalytic agent, and thencombining the bleaching agent with the catalytic agent, such that thecatalytic agent catalyzes the reaction of a significant portion of thebleaching agent within about ten minutes of combining the bleachingagent with the catalytic agent.

Any convenient means can be utilized for separating the bleaching agentfrom the catalytic agent prior to the reaction process. In oneembodiment, separate containers are used, one of which holds thebleaching agent in liquid form, and one of which holds the catalyticagent in solid or liquid form. The bleaching agent is then mixed withthe catalytic agent immediately prior to use. For example, the bleachingagent can be in a liquid form, similar to a mouthwash. The catalyticagent can be in the form of a solid powder, contained in a foil packet.Just prior to use, the catalytic agent is added to the liquid containingthe bleaching agent and the liquid is retained in the mouth, similar toa mouthwash, for three to five minutes.

In another embodiment, a single container can be compartmentalized sothe bleaching agent is housed separately from the catalytic agent. Uponextrusion form the dual compartment container the bleaching agent iscombined with the catalytic agent. For example, the whitening agent andcatalytic agents can each be contained in a gel or paste form. Uponextrusion from the container, the two are admixed, and placed on atoothbrush. Brushing for three to five minutes can also result in mixingthe catalytic agent with the bleaching agent.

In another embodiment, a stable composition is formed consisting of thecatalyst microencapsulated and mixed with the bleaching agent.Techniques for microencapsulation of individual components for tooth andgum dentifrice are well known in the art (see U.S. Pat. No. 5,403,578).The encapsulated material is stable until contacted with water. In thisembodiment it is preferable for the base composition of the paste to befree of water. Upon use of the composition, and the addition of water,the bleaching agent is placed in contact with the catalyst.

Either a paste or gel containing the bleaching agent and the catalystmay be prepared. Alternatively, a fabric embedded with the bleachingagent and the catalyst can be produced. Upon the addition of water,thereby wetting the fabric, the bleaching agent and the catalyst areadmixed.

In another embodiment, the catalytic agent can be applied on a solidsurface, such as a dental tray (e.g., U.S. Pat. No. 4,990,089). Thedental tray can be either pre-fabricated or customized. In order toproduce a customized dental tray, a sheet of moldable plastic is usedthat will conform to a mold of an individual's teeth. Production of suchtrays is well known in the art. In brief: (1) a mold of the teeth to bewhitened is prepared, (2) a sheet of plastic material of a appropriatesize between 0.01 inch and 0.1 inch thick is obtained, (3) the plasticsheet is placed in a holder, and, if desired, silicone may be sprayedonto the plastic sheet, (4) the plastic sheet is heated until it becomesmalleable, (5) the heated sheet is placed over the model, (6) the heatedplastic is contoured to the mold, either manually or using a vacuumprocess, (7) the mold is removed, and (8) the plastic is trimmed. Thecatalytic agent may be embedded into a sponge which is inserted into theheated plastic. Alternatively, the catalytic agent can be embedded in afabric which is bonded to the tray after the plastic has cooled. Thecatalytic agent can also be directly applied or bonded to the surface ofthe to the cooled plastic, such as by spraying the tray with a solutionof copper salts. The bleaching agent is applied to the tray in the formof a paste or a liquid immediately prior to use, and the tray is thenapplied to the subject's teeth.

In another embodiment, the catalytic agent may be applied to the surfaceof a toothbrush. A "toothbrush" is a device designed for cleaning teeththat has a region for holding, such as a handle, and a region forcleaning, such as bristles or a sponge. The toothbrush is eithermanually or mechanically agitated to clean the teeth of a subject. Thehead of the brush can be made of any appropriate material, such asplastic, and can be designed to contain the catalyst, either by applyingthe catalytic agent directly to the head of the brush, either on thesame side of the brush as the bristles or sponge, or on the oppositeside of the brush. The catalytic agent can be embedded in a fabric thatis bonded to the head of the brush, or the fabric embedded with thecatalytic agent can be inserted into a compartment in the head of thebrush.

Referring to FIG. 1 there is shown a toothbrush, comprising a handle (1)and a head (2). The head (2) comprises bristles (3) and a compartment(4) for the insertion of a fabric or gel foam comprising a catalyticagent. The fabric or gel foam comprising the catalytic agent may beremoved and replaced with a new piece of fabric or gel foam comprising acatalytic agent when desired.

A front elevational view of the device shown in FIG. 1, where a sectionis shown looking is the direction of (A), is depicted in FIG. 2.Referring to FIG. 2 it can be seen that the compartment (4) in the headof the brush is open to the upper surface of the brush. The bleachingcompound is applied to the bristles prior to use of the toothbrush bythe subject; the application of the bleaching compound to the toothbrushresults in the catalyst contacting the bleaching compound. The subjectthen uses the toothbrush to brush the teeth, and the whitening effect isthereby achieved.

Alternatively, the bristles located on the head of the tooth brush canbe designed to contain the catalyst: the catalyst can be applied to thesurface of the bristle or it can be embedded into one or more of thebristles of the brush. Referring to FIG. 3, there is shown a toothbrushwith a handle (5) and a head (6) with bristles (7). One of the of thebristles (8) is embedded with a catalytic agent. It should be noted thatany number or conformation of bristles can be embedded with thecatalytic agent. The bleaching compound is applied to the bristles priorto use of the toothbrush by the subject; the application of thebleaching compound to the toothbrush results in the catalyst contactingthe bleaching compound. The subject then uses the toothbrush to brushthe teeth, and the whitening effect is thereby achieved.

The following examples are intended to illustrate but not to limit theinvention in any manner, shape, or form, either explicitly orimplicitly. While they are typical of those that might be used, otherprocedures, methodologies, or techniques known to those skilled in theart may alternatively be used.

EXAMPLES Example 1

Stained extracted teeth were sectioned into two equal pieces. Each ofthe pieces was submerged into a peroxide solution or gel. One piece ofeach tooth was submerged in peroxide alone, while the other wassubmerged in hydrogen peroxide with a catalyst, a hydrogen peroxidecontaining a modifier to raise the pH (either AMP or tris-Amino), orhydrogen peroxide containing both the catalyst and the modifier. Threesolutions were tested: (1) 3% hydrogen peroxide, (2) 6% hydrogenperoxide, and (3) 10% hydrogen peroxide. Two gels were tested: (1) acommercially available dentist-supervised bleaching gel containinghydrogen peroxide up to 7%, and (2) a commercially availabledentist-supervised bleaching gel containing carbamide peroxide up to20%. Two catalysts were used in the experiments, either a standardactivated charcoal or Centaur (Calgon) activated charcoal. Samples werephotographed after three minutes of exposure, and at several other timepoints.

When a catalyst was used, significant bleaching was noted after twelveminutes. The bleaching was comparable to between 21 and 30 hours ofbleaching without the catalytic agent. It was noted that those gelscontaining large amounts of carbopol provided the least amount of dentalbleaching.

Example 2

A catalytic agent was applied to a toothbrush by dipping a wettoothbrush into powdered catalytic agent, or by bonding activatedcharcoal to a toothbrush head between the bristles. A whitening gel(Natural White) containing 1.5% hydrogen peroxide was applied to thetoothbrush and the brush was used to clean a subject's teeth. Awhitening effect was noted after one application of three minutes induration. One subject repeated the application of the whitening gel inthe presence of the catalytic agent twice a day for three days.Significant whitening was noted following three days of application.

Example 3

Liquid 3% hydrogen peroxide was mixed with a few drops a mint flavor. Asmall amount of activated charcoal catalytic agent was placed into acup, and one-half teaspoon of the peroxide was added. This solution wasused to bathe the teeth of subjects for sessions fo three minutes ofduration, carried out for twice a day over a period of several days.Visible whitening was noted after two days.

It is to be understood that this invention is not limited to theparticular methodology, and that protocols, apparatus, models andreagents described as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to limit thescope of the present invention which will be limited only by theappended claims.

Example 4

A specific formulation of the bleaching compound is as follows:

    ______________________________________                                                        Concentration                                                 Component       (percent by weight)                                           ______________________________________                                        Hydrogen peroxide                                                                               10%                                                         flavoring agent   1%                                                          aloe vera         2%                                                          potassium nitrate                                                                               1%                                                          titanium dioxide                                                                                1%                                                          sodium lauryl sulfate                                                                          1.5%                                                         paste carrier   83.5%                                                         ______________________________________                                    

In one embodiment, for use with the method of the invention, a catalystis prepared consisting of activated charcoal and AMP mixed in the ratioof 2:1. The formulation comprising the bleaching compound and thecatalyst are combined at the time of use in the ratio of 10:1.

In another embodiment, for use with a device of the invention, theformulation comprising the bleaching compound is placed on thetoothbrush with a catalyst embedded into one or more of the bristles ofthe brush, or with a catalytic agent embedded in a fabric bonded to thehead of the brush.

What is claimed is:
 1. A device for whitening teeth, said devicecomprisinga toothbrush comprising a head and a handle, said head havinga plurality of bristles, wherein at least one bristle comprises acatalytic activator, and said handle comprising a reservoir for ableaching compound and a means for dispensing said bleaching compound inclose proximity to said bristles.
 2. The device of claim 1, wherein saidbleaching compound is selected from the group consisting of carbamideperoxide, carbamyl peroxide, sodium percarbonate, perhydrol urea, andhydrogen peroxide.
 3. The device of claim 1, wherein said catalyticactivator is selected from the group consisting of activated charcoal,platinum, a platinum salt, copper, a copper salt, palladium, a palladiumsalt, silver, and a silver salt.
 4. A device for whitening teeth, saiddevice comprising;a toothbrush comprising a head and a handle, said headcomprising an applicator and a catalytic activator capable of catalyzingthe reaction of a bleaching compound applied to said head.
 5. The deviceof claim 4, wherein said head further comprises a retaining means forholding a bleaching agent in solid form.
 6. The device of claim 4,wherein said applicator is a plurality of bristles.
 7. The device ofclaim 4, wherein said bleaching compound is selected from the groupconsisting of carbamide peroxide, carbamyl peroxide, sodiumpercarbonate, perhydrol urea, and hydrogen peroxide.
 8. The device ofclaim 4, wherein said catalytic activator is selected from the groupconsisting of activated charcoal, platinum, a platinum salt, copper, acopper salt, palladium, a palladium salt, silver, and a silver salt.